Deuteronomy 16:9
“Seven weeks shalt thou number unto thee: begin to number the seven weeks from such time as thou beginnest to put the sickle to the corn.”
And thou shalt roast and eat it in the place which the Lord thy God shall choose: and thou shalt turn in the morning, and go unto thy tents.
Six days thou shalt eat unleavened bread: and on the seventh day shall be a solemn assembly to the Lord thy God: thou shalt do no work therein.
Seven weeks shalt thou number unto thee: begin to number the seven weeks from such time as thou beginnest to put the sickle to the corn.
And thou shalt keep the feast of weeks unto the Lord thy God with a tribute of a freewill offering of thine hand, which thou shalt give unto the Lord thy God, according as the Lord thy God hath blessed thee:
And thou shalt rejoice before the Lord thy God, thou, and thy son, and thy daughter, and thy manservant, and thy maidservant, and the Levite that is within thy gates, and the stranger, and the fatherless, and the widow, that are among you, in the place which the Lord thy God hath chosen to place his name there.
Counter-Arguments
The strongest case that this verse does not belong in this theme.

Cross-References
“And the feast of harvest, the firstfruits of thy labours, which thou hast sown in the field: and the feast of ingathering, which is in the end of the year, when thou hast gathered in thy labours out of the field.”
“And thou shalt observe the feast of weeks, of the firstfruits of wheat harvest, and the feast of ingathering at the year’s end.”
“And ye shall count unto you from the morrow after the sabbath, from the day that ye brought the sheaf of the wave offering; seven sabbaths shall be complete:”
“For I will promote thee unto very great honour, and I will do whatsoever thou sayest unto me: come therefore, I pray thee, curse me this people.”
“Also in the day of the firstfruits, when ye bring a new meat offering unto the Lord, after your weeks be out, ye shall have an holy convocation; ye shall do no servile work:”